In order to fully exercise the body, a person must often obtain a set of exercise equipment, the components of which are designed to exercise each part of the body separately. As a result, one part of the body is often exercised more than the rest, so that a uniform benefit is not achieved.
For example, dumbbells of varying weights are commonly used for exercising the arms and shoulders, but cannot be used effectively for exercising the wrists and fingers. In addition, small dumbbells must be used for exercising weaker muscles, and larger dumbbells must be used for exercising stronger muscles, such as the biceps. Some dumbbells, such as those disclosed in U.S. Pat. Nos. 4,695,051, 4,913,422, and 4,854,575, are filled with a liquid or other heavy substance such as sand, to allow adjustment of the weight of the dumbbell for exercising different muscles. However, modifying the weight of these devices is a cumbersome process.
A number of complex, multicomponent exercise devices have been recently advertised for exercising parts of the body such as the legs, thighs, and chest. These devices typically incorporate sliding or scissored arms biased by springs, elastic bands or pneumatic cylinders to provide an opposing force against the user. These devices are commonly expensive, difficult to use and have the particular disadvantage of exercising at most two or three parts of the body.
The technical literature regarding exercising has stressed the importance of a “full body” workout. It has been recognized that selectively training certain parts of the body at the expense of others can lead to health problems in those parts of the body that are not exercised. Furthermore, neglect of certain muscle groups can lead to balance problems and an overall loss of athletic performance. In particular, this need for a full body workout has led to the recent trend of “cross-training,” i.e., training in several sports simultaneously so as to exercise all parts of the body.
Cross training, however, can be very expensive, for the simple reason that athletic gear and equipment is required for each of the several individual sports or exercises in which the athlete attempts to engage.